BRASILIA, May 8 (Reuters) - The Brazilian government is trying to secure a “safe margin” of votes in favor of its proposal to overhaul the country’s costly social security system, Finance Minister Henrique Meirelles told journalists on Monday after a Victory Day parade.

A vote in the full house planned for this week has been put back to allow the government coalition to muster the 308 votes needed. Pension reform is a contentious issue in Brazil, which has one of the world’s most generous social security systems, allowing retirement on average at the age of 54 with almost full benefits, compared with 72 years in Mexico. (Reporting by Rodrigo Viga Gaier; Writing by Silvio Cascione)